Screen wont "Sleep"?

Am I missing a setting or something? Basically, I forgot my test device on while in my app and 20 minutes later the screen was still active. How do I make my game put the screen into sleep mode after no activity for a bit?

I think it was decided to keep the screen on because of apps not requiring touch input for some time (using accelerometer or playing animations) and it had to be either always on or sleep when device requested it. IOS version was already doing the same at that point.

I for one am happier with always on if these are the two options since I use accelerometer for some of my games and they went to sleep on most devices if the screen was not touched.

@vafurlogi said:
I think it was decided to keep the screen on because of apps not requiring touch input for some time (using accelerometer or playing animations) and it had to be either always on or sleep when device requested it. IOS version was already doing the same at that point.

I for one am happier with always on if these are the two options since I use accelerometer for some of my games and they went to sleep on most devices if the screen was not touched.